This invention relates to a method and apparatus for drilling oil and gas wells whether onshore or offshore.
More specifically, this invention is directed to an improvement in drive systems for rotary drilling and reaming operations without a kelly or kelly bushing.
There are two known drive systems for drilling oil and gas wells without the kelly and kelly bushing. These systems are the top drive drilling system and the side drive drilling system. A top drive system is shown and described in the U.S. Pat. Nos. 4,421,179, 4,449,596 and 4,458,768 to Boyadjieff and a side drive system is shown and described in the U.S. Pat. Nos. 4,685,915 to Goris and 4,875,529 to Wetch et al. The latter is characterized as being rail-less. Other patents related to this matter are U.S. Pat. Nos. 4,437,524 and 3,009,521.
The top drive system requires a large power source at the top of the drill string and travels up and down with the drill string and the side drive system transfers the power from the rotary table to the top of the drill string through a drive assembly which moves along a vertical drive shaft. Both these systems have advantages including the capability of drilling and reaming in triples and have performed very well even though both systems require the torque transfer means to travel the full length from the rig to the top of the derrick and visa versa.
On the other hand, there has always been a need to drive the drill pipe for drilling or reaming close to the power source on the floor of the drilling rig using the existing source of rotation without adding expensive secondary means and without a kelly or kelly bushing and this invention fulfills this need.
As will be apparent from a study of the following, this invention is a floor drive rotary drilling system without a kelly or kelly bushing and has a number of advantages;
uses the existing source of rotation,
does not interfere with conventional rotary table drilling operations,
provides a drilling system which is positionable directly on the drilling rig floor and thus does not require movable overhead power systems above the rig floor,
requires only a portion of the drive system to travel in contrast to the prior art systems which require the entire drive system to travel downward and upward with the drill string between the rig floor and the top of the derrick during drilling and reaming operations, and
is releasably and easily coupled to a selected drilling rig to allow temporary placement on a selected rig thus allowing the invention to selectively serve a number of drilling rigs.